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Subject[patch 40/60] ext4: fix bogus BUG_ONs in in mballoc code

-stable review patch. If anyone has any objections, please let us know.

------------------
From: Eric Sandeen <sandeen@redhat.com>

(cherry picked from commit 8d03c7a0c550e7ab24cadcef5e66656bfadec8b9)

Thiemo Nagel reported that:

# dd if=/dev/zero of=image.ext4 bs=1M count=2
# mkfs.ext4 -v -F -b 1024 -m 0 -g 512 -G 4 -I 128 -N 1 \
-O large_file,dir_index,flex_bg,extent,sparse_super image.ext4
# mount -o loop image.ext4 mnt/
# dd if=/dev/zero of=mnt/file

oopsed, with a BUG_ON in ext4_mb_normalize_request because
size == EXT4_BLOCKS_PER_GROUP

It appears to me (esp. after talking to Andreas) that the BUG_ON
is bogus; a request of exactly EXT4_BLOCKS_PER_GROUP should
be allowed, though larger sizes do indicate a problem.

Fix that an another (apparently rare) codepath with a similar check.

Reported-by: Thiemo Nagel <thiemo.nagel@ph.tum.de>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
fs/ext4/mballoc.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -1450,7 +1450,7 @@ static void ext4_mb_measure_extent(struc
struct ext4_free_extent *gex = &ac->ac_g_ex;

BUG_ON(ex->fe_len <= 0);
- BUG_ON(ex->fe_len >= EXT4_BLOCKS_PER_GROUP(ac->ac_sb));
+ BUG_ON(ex->fe_len > EXT4_BLOCKS_PER_GROUP(ac->ac_sb));
BUG_ON(ex->fe_start >= EXT4_BLOCKS_PER_GROUP(ac->ac_sb));
BUG_ON(ac->ac_status != AC_STATUS_CONTINUE);

@@ -3400,7 +3400,7 @@ ext4_mb_normalize_request(struct ext4_al
}
BUG_ON(start + size <= ac->ac_o_ex.fe_logical &&
start > ac->ac_o_ex.fe_logical);
- BUG_ON(size <= 0 || size >= EXT4_BLOCKS_PER_GROUP(ac->ac_sb));
+ BUG_ON(size <= 0 || size > EXT4_BLOCKS_PER_GROUP(ac->ac_sb));

/* now prepare goal request */




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